German Chancellor Angela Merkel listens to questions during a news conference at the end of a euro zone leaders summit in Brussels, Belgium, July 13, 2015. [Photo/Agencies]

Tsipras will now have to rush swathes of legislation through parliament this week to convince his 18 partners to release bridging funds to avert a state bankruptcy and just to begin negotiations on a three-year loan.

If the summit had failed, Greece would have be staring into an economic abyss with its shuttered banks on the brink of collapse and the prospect of having to print a parallel currency and in time exit the European monetary union.

Six sweeping measures including spending cuts, tax hikes and pension reforms must be enacted by Wednesday night and the entire package endorsed by parliament before talks can start, the leaders decided.

In almost the only concession after imposing a tough set of terms on Tsipras, Germany dropped a proposal to make Greece take a "time-out" from the euro zone that many said resembled a forced ejection if it failed to meet the conditions.

Tsipras said on arrival in Brussels on Sunday he wanted "another honest compromise" to keep Europe united. Instead, he was subjected to a 15-hour humiliation by leaders furious that he had spurned their previous bailout offer on more favourable terms in June and held a referendum last week to reject it.

One senior EU official calculated the cost to the Greek state of the last two weeks of political and economic turmoil at 25 to 30 billion euros.